Ralph Menikoff

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Pressure-volume-temperature (PVT) equation-of-state (EOS) information for polymers and polymeric composites is valuable for predicting their response to extreme conditions. An obstacle in determining equations of state for polymeric materials is the lack of a simple, static experimental method for acquiring PVT data for solid networks and liquids at(More)
Yet for numerical simulations of detonation waves in plastic binded explosives (PBX) empirical pressure dependent reaction rates, such as ``Forest fire'' or the ``Ignition and Growth'' model, are typically used. The underlying reason for this disparity between between fundamental chemical rate laws and empirical burn models is due to the fact that a PBX is(More)
Atomistic simulations were used to calculate the isothermal elastic properties for b-, a-, and d-octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine ~HMX!. The room-temperature isotherm for each polymorph was computed in the pressure interval 0<p<10.6 GPa and was used to extract the initial isothermal bulk modulus Ko and its pressure derivative using equations(More)
We present a novel linear solver that works well for large systems obtained from discretizing PDEs. It is robust and, for the examples we studied, the computational eeort scales linearly with the number of equations. The algorithm is based on a wavelength decomposition that combines conjugate gradient, multi-scaling and iterative splitting methods into a(More)
We are developing a new high explosive pulsed power (HEPP) system based on the 1.4 m long Ranchero generator which was developed in 1999 for driving solid density z-pinch loads. The new application requires approximately 40 MA to implode similar liners, but the liners cannot tolerate the 65&#x00B5;s, 3 MA current pulse associated with delivering the initial(More)
A simple extension of a conventional two-phase continuum model of Deflagration-to-Detonation Transition (DDT) in energetic granular material is given to account for energy dissipation induced by quasi-static compaction. To this end, the conventional model equations are supplemented by a relaxation equation that accounts for irreversible changes in solid(More)
Foams, porous solids and granular materials have a characteristic Hugoniot locus that for weak shocks is concave in the (particle velocity, shock velocity)-plane. An equation of state (EOS) that has this property can be constructed implicitly from a Helmholtz free energy of the form Ψ(V;T;φ) = Ψs(V;T )+B(φ) where the equilibrium volume fraction φeq is(More)
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